Thermodynamic Properties of Argon

Temperature Pressure Density Volume Int. energy Enthalpy Entropy C, CT Sound speed Joule-Thomson Therm, cond. Viscosity 

The estimated uncertainty in density is less than 0.02% for pressures up to 12 MPa and temperatures up to 340 K with the exception of the critical region and less than 0.03% for pressures up to 30 MPa and temperatures between 235 and 520 K. Elsewhere, the uncertainty in density is generally within 0.2%. In the region with densities up to one-half the critical density and for temperatures between 90 and 450 K, the estimated uncertainty of calculated speeds of sound is in general less than 0.02%. In the liquid and supercritical regions, the uncertainty is less than 1%. The uncertainty in heat capacities is within 0.3% for the vapor and 2% for the liquid. The formulation gives reasonable extrapolation behavior up to very high pressures (50 GPa) and temperatures (17,000 K). 

For viscosity, the uncertainty is 0.5% in the dilute gas. Away from the dilute gas (pressures greater than 1 MPa and in the liquid), the uncertainties are as low as 1% between 270 and 300 K at pressures less than 100 MPa, and increase outside that range. The uncertainties are around 2% at temperatures of 180 K and higher. Below this and away from the critical region, the uncertainties steadily increase to around 5% at the triple points of the fluids. The uncertainties in the critical region are higher. 

For thermal conductivity, the uncertainty for the dilute gas is 2% with increasing uncertainties near the triple point. For the nondilute gas, the uncertainty is 2% for temperatures greater than 170 K. The uncertainty is 3% at temperatures less than the critical point and 5% in the critical region, except for states very near the critical point. 

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TABLE 2 Thermodynamic properties of argon" (All quantities are in units of J K moM)... 

Recently we reported calculations on the thermodynamic properties of argon clusters modeled by pairwise additive Lennard-Jones interactions... 

Stewart RB, Jacobsen RT. Thermodynamic properties of argon from the triple point to 1200 K with pressures to 1000 MPa. J Phys Chem Ref Data 1989 18 639. 

Weakleim, C. L., and Reiss, H. (1993) Toward a molecular theory of vapor-phase nucleation. III. Thermodynamic properties of argon clusters from Monte Carlo simulations and a modified liquid drop theory, J. Chem. Phys. 99, 5374-5383. 

C. L. Briant and J. J. Burton, Molecular dynamics study of the structure and thermodynamic properties of argon microclusters, J. Chem. Phys. 63, 2045-2058 (1975). 

A. L. Gosman, R. D. McCarty, and J. G. Hust, Thermodynamic Properties of Argon from the Triple Point to 300 K at Pressures to 1000 Atmospheres , National Standard Reference Data Series-National Bureau of Standards, NSRDS-NBS 27, 1969. 

McDonald I R and Singer K 1967 Calculation of thermodynamic properties of liquid argon from Lennard-Jones parameters by a Monte Carlo method Discuss. Faraday Soc. 43 40-9... 

Computes thermodynamic properties of air, argon, carbon monoxide, carbon dioxide, hydrogen, nitrogen, oxygen, water vapor, and products of combustion for hydrocarbons. Computes all properties from any two independent properties. 

V. A. Rabinovich, A. A. Vasserman, V. I. Nedostup, and I. S. Veksler, Thermodynamic Properties of Neon, Argon, Krypton and Xenon, Springer, Berlin, 1988. 

L. V. Gurvich, I. V. Veyts, and C. B. Alcock, Thermodynamic Properties of Individual Substances, Vol. 1 Elements Oxygen, Hydrogen (Deuterium, Tritium), Fluorine, Chlorine, Bromine, Iodine, Helium, Neon, Argon, Krypton, Xenon, Radon, Sulfur, Nitrogen, Phosphorus, and Their Compounds, Pt. 1 Methods and Computation, Hemisphere, New York, 1989. 

In an attempt both to include quantum corrections and to treat anharmonic effects, Etters, Kanney, Gillis, and Kaelberger have calculated the thermodynamic properties of clusters using the self-consistent phonon approximation. - Within this approximation they calculated internal energies, free energies, specific heats, and entropies for argon clusters. 

FIG. 2-5 Pressure-enthalpy diagram for dry air. Properties computed with the NIST REFPROP Database, Version 7.0 (Lemmon, E. W., McLinden, M. O., and Huber, M. L., 2002, NIST Standard Reference Database 23, NIST Reference Fluid Thermodynamic and Transport Properties—REFPROP, Version 7.0, Standard Reference Data Program, National Institute of Standards and Technology), based on the equation of state of Lemmon, E. W., Jacobsen, R. T., Penoncello, S. G., and Friend, D. G., Thermodynamic Properties of Air and Mixtures of Nitrogen, Argon, and Oxygen from 60 to 2000 K at Pressures to 2000 MPa, /, Phys. Chem. Ref. Data 29 331-385, 2000. 

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